Microwave plasma processing device, plasma processing method, and microwave radiating member

ABSTRACT

A placement stage ( 24 ) on which a semiconductor wafer (W) is place is provided within a processing container ( 22 ). A microwave is generated by a microwave generator ( 76 ), and the microwave is introduced into a process container ( 22 ) through a flat antenna member ( 66 ). The flat antenna member ( 66 ) has a plurality of slots ( 84 ) arranged along a plurality of circumferences, and the plurality of circumferences are non-concentric to each other. A distribution of plasma density in the flat antenna member ( 66 ) in a radial direction is uniform.

TECHNICAL FIELD

The present invention relates to plasma processing apparatuses and, moreparticularly, to a microwave plasma processing apparatus and a plasmaprocessing method for acting plasma generated by a microwave onto anobject to be processed such as a wafer, etc.

BACKGROUND ART

In recent years, with densification and miniaturization of semiconductorproducts, plasma processing apparatuses have been used for a processsuch as film deposition, etching, ashing, etc. in a manufacturingprocess of a semiconductor product. Especially, a microwave plasmaprocessing apparatus that generates plasma using a microwave is capableof stably generating plasma even in a high-vacuum state of a relativelylow pressure such as 0.1-10 mToor. For this reason, a microwave plasmaprocessing apparatus using 2.45 GHz microwave, for example, hasattracted attention.

Generally, in a microwave plasma processing apparatus, a dielectricplate that can transmit a microwave is provided to a ceiling part of aprocess container which is made to be evacuatable, and a disc-like, flatantenna member (microwave radiation member) is attached to thedielectric plate. Many through holes (slots) are formed in the antennamember so as to introduce a microwave, which is supplied at the centerthereof and propagates in radial directions, into the process containerthrough the slots. Plasma of a process gas is generated by the microwaveintroduced into the process container, and plasma processing is appliedto the semiconductor wafer placed in the process container.

Japanese Patent Publications No. 2722070 and No. 2928577 disclose amicrowave plasma processing apparatus having an antenna member forintroducing a microwave into a process container. The antenna memberdisclosed in these patent publications has a circular shape, and manyslots or slot pairs are formed along a plurality of concentric circles.Also disclosed is an antenna member having many slots or slot pairsarranged spirally.

A microwave supplied to the central part of the circular antenna memberpropagates in a radial direction, and the direction is changed by theslots and is introduced into the process container after passing throughthe dielectric plate. Under such a condition, a surface wave propagatingin radial directions (through the dielectric plate) between the antennamember and the plasma is reflected by an outer peripheral surface of thedielectric plate and returns to the central part. Here, in a case wherethe slots of the antenna member are arranged along a plurality ofconcentric circles, the surface wave reflected by the entire peripheralsurface of the dielectric plate is concentrated into the central part ofthe antenna member. Therefore, the electric field of the surface wave islarge at the central part of the antenna, and decreases toward theperipheral parts.

FIG. 1 is an illustration showing propagation of the surface wave in theantenna member having concentrically arranged slots and a distributionof an electron density in a plasma space. FIG. 1(a) shows surface wavepropagation of the dielectric plate in correspondence to the antennamember, and FIG. 1(b) is a graph showing a distribution of electrondensity of a plasma density in a radial direction of the antenna member.As shown in FIG. 1(b), the electron density ne of the plasma space ismaximum at the central part of the antenna member, and the electrondensity ne decreases toward the periphery of the antenna member.Therefore, in the antenna member having concentrically arranged slots,there is a problem in that the plasma density is uneven since the plasmadensity corresponding to the central part of the antenna member ishigher than the plasma density in the periphery.

DISCLOSURE OF INVENTION

It is a general object of the present invention to provide an improvedand useful microwave plasma processing apparatus and a plasma processingmethod in which the above-mentioned problems are eliminated.

A more specific object of the present invention is to provide amicrowave plasma processing apparatus, a plasma processing method and anantenna member which can make a plasma density uniform in a radialdirection of an antenna member.

In order to achieve the above-mentioned objects, there is providedaccording to one aspect of the present invention a microwave plasmaprocessing apparatus which applies plasma processing to a substrate tobe processed comprising: a process container provided therein with aplacement stage on which the substrate to be processed is placed; amicrowave generator which generates a microwave and supplies themicrowave to the process container; and a microwave radiation memberprovided between the microwave generator and the process container so asto radiate the microwave to a space of the process container, whereinthe microwave radiation member has a plurality of slots arranged along aplurality of circumferences, and the plurality of circumferences arenon-concentric to each other.

In the above-mentioned invention, the centers of the plurality ofcircumferences may be eccentric in different directions to each otherwith respect to the center of the microwave radiation member.Additionally, the centers of the plurality of circumferences may beeccentric in the same direction to each other with respect to the centerof the microwave radiation member, and an amount of eccentricity of thecenters of the plurality of circumferences may increase toward aperiphery of the microwave radiation member. Further, a slot pair may beformed by one of the slots and an adjacent one of the slots arranged ina T-shape, and a plurality of the slot pairs may be arranged along theplurality of circumferences.

Additionally, there is provided according to another aspect of thepresent invention a plasma processing method using a microwave plasmaprocessing apparatus which applies plasma processing to a substrate tobe processed, comprising; a process container provided therein with aplacement stage on which the substrate to be processed is placed; amicrowave generator which generates a microwave and supplies themicrowave to the process container; and a microwave radiation memberprovided between the microwave generator and the process container so asto radiate the microwave to a space of the process container, whereinthe microwave radiation member has a plurality of slots arranged along aplurality of circumferences, and the plurality of circumferences arenon-Concentric to each other, the method comprising: placing thesubstrate to be processed on the placement stage so that a processingsurface of the substrate faces the microwave radiation member; supplyingthe microwave to the microwave radiation member so as to introduce themicrowave into the process container through the non-concentricallyarranged slots; and generating plasma in the process container by theintroduced microwave so as to apply a plasma process to the substrate bythe generated plasma.

Additionally, there is provided according to another aspect of thepresent invention a microwave radiation member used for a microwaveplasma processing apparatus comprising a process container which appliesa plasma process and a microwave generator which generates a microwaveand supplies to the process container, wherein the microwave radiationmember is attached to the process container and is connected to themicrowave generator, and the microwave radiation member has a pluralityof slots arranged along a plurality of circumferences non-concentric toeach other so as to introduce the microwave into the process containerthrough the plurality of slots.

In the above-mentioned invention, the centers of the plurality ofcircumferences may be eccentric in different directions to each otherwith respect to the center of the microwave radiation member.Additionally, the centers of the plurality of circumferences may beeccentric in the same direction to each other with respect to the centerof the microwave radiation member, and an amount of eccentricity of thecenters of the plurality of circumferences may increase toward aperiphery of the microwave radiation member. Further, a slot pair may beformed by one of the slots and an adjacent one of the slots arranged ina T-shape, and a plurality of the slot pairs may be arranged along theplurality of circumferences.

According to the above-mentioned invention, the density of plasma togenerate can be uniformized by arranging the plurality of slots of themicrowave radiation member along the plurality of non-concentriccircumferences. By making the plurality of non-concentric circumferenceseccentric in different directions, the electron density, which tends toincrease at the central part of the microwave radiation member, can bedecreased so as to uniformize the plasma density. Moreover, the plasmadensity can be uniformized by intentionally generating a variation inthe distribution of electron density by making the plurality ofnon-concentric circumferences eccentric in the same direction andcorrecting by synthesizing with a variation of the plasma density due toother causes.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed description when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration showing propagation of a surface wave in anantenna member having concentrically arranged slots and a distributionof electron density in a plasma space.

FIG. 2 is a cross-sectional view showing an outline structure of amicrowave plasma processing apparatus which is provided with an antennamember according to a first embodiment of the present invention.

FIG. 3 is a plan view of the antenna member shown in FIG. 2.

FIG. 4 is a graph showing the distribution of electron density whenusing the flat antenna member according to the first embodiment of thepresent invention.

FIGS. 5A-5F are illustrations showing plane configurations of the slot.

FIG. 6 is a plan view of a flat antenna member using T-shaped slotpairs.

FIG. 7 is a plan view of a flat antenna member according to a secondembodiment of the present invention.

FIG. 8 is a graph showing a distribution of electron density generatedby the flat antenna member shown in FIG. 7.

FIG. 9 is a graph for explaining a structure to correct a variation inelectron density by the flat antenna member shown in FIG. 7.

BEST MODE FOR CARRYING OUT THE INVENTION

A description will be given below, with reference to the drawings, ofembodiments according to the present invention. It should be noted thatthe same parts in the figures are give the same reference numerals.

FIG. 2 is a cross-sectional view showing an outline structure of amicrowave plasma processing apparatus which is provided with an antennamember according to a first embodiment of the present invention. Itshould be noted that the microwave plasma processing apparatus shown inFIG. 2 is a plasma CVD processing apparatus as an example.

The plasma CVD apparatus 20 shown in FIG. 2 has a process container 22which is formed in a cylindrical shape in its entirety. The processcontainer 22 is constituted by a conductor such as aluminum, and forms aclosed process space S therein.

A placement stage 24 on which a semiconductor wafer W as an object to beprocessed is placed is accommodated in the process container 22. Theplacement stage 24 is formed in a generally cylindrical shape with aprotruding central part by, for example, an anodized aluminum. The lowerpart of the placement stage 24 is supported by a support base 26 whichis also formed in a cylindrical-shape by aluminum etc. The support base26 is installed on a bottom of the process container 22 through aninsulating material 28.

The upper surface of the placement stage 24 is provided with anelectrostatic chuck or a clamp mechanism (not shown) for holding thesemiconductor wafer W. The placement stage 24 is connected to a matchingbox 32 and a high-frequency power source 34 for bias through a powersupply line 30. Although the high-frequency power source for biasgenerates and supplied a high-frequency wave of 13.56 MHz, it is notalways necessary to provide.

The support base 26, which supports the placement stage 24, is providedwith a cooling jacket 36 through which a cooling water flows for coolingthe wafer W during plasma processing. It should be noted that a heaterfor heating may be incorporated into the placement stage 24 if needed.

Provided on the side wall of the process container are a quartz plasmagas supply nozzle 38 which supplies a gas for plasma such as, forexample, argon gas and a quartz process gas nozzle 40 introduces aprocess gas such as, for example, a deposition gas. The nozzles 38 and40 are connected to the plasma gas source 54 and a process gas sourcevia mass-flow controllers 46 and 48 and open/close valves 50 and 52,respectively. SiH₄, O₂, N₂ gas etc. are used for a deposition gas as aprocess gas.

Additionally, a gate valve 58, which opens and closes when carrying inand taking out the wafer W to the inside, is provided on the outerperiphery of the sidewall of the process container 22. Moreover, anexhaust port 60 connected to a vacuum pump (not shown) is provided onthe bottom of the process container 22 so that the inside of the processcontainer 22 can be evacuated to a predetermined pressure if needed.Then, the ceiling part of the process container 22 is open, and adielectric plate 62 is airtightly provided thereto via a seal member 64,the dielectric plate 62 being made of a ceramic material such asaluminum nitride AlN or aluminum oxide Al₂O₃ or silicon oxide SiO₂. Thethickness of the dielectric plate 62 is 20 mm, for example, and haspermeability to microwaves.

Provided on the upper surface of the dielectric plate 62 is a disc-likeflat antenna member (microwave radiation member) 66. Specifically, theflat antenna member 66 is constituted as a bottom plate of a waveguidebox 68, which forms a hollow cylindrical container and is integrallyformed with the process container 22. The flat antenna member 66 isprovided so as to face the placement stage 24 in the process container22. At the center of an upper part of the waveguide box 68, an outerconductor 70A of a coaxial waveguide 70 is connected, and an innerconductor 70B inside is connected to the central part of the antennamember 66. Then, the coaxial waveguide 70 is connected to a 2.45 GHzmicrowave generator 76 through a mode converter 72 and a waveguide 74 soas to propagate a microwave to the flat antenna member 66. The frequencyof the microwave is not limited to 2.45 GHz, and, for example, 8.35 GHzmay be used. As for the waveguide, a waveguide having a circular crosssection or a rectangular cross section or a coaxial waveguide can beused. The coaxial waveguide is used in the microwave plasma processingapparatus shown in FIG. 2. Additionally, a wave retardation member 82,which is made of, for example, Al2O3 and has a predeterminedpermittivity and a predetermined thickness, is provided on the uppersurface of the flat antenna member 66 so as to reduce a wavelength ofthe microwave in the waveguide due to a wavelength reducing effectthereof. It should be noted that the wave retardation member 82 may beprovided if needed.

Next, a description will be given in detail, with reference to FIG. 3,of the flat antenna member 66 as a microwave radiation member accordingto the first embodiment of the present invention. FIG. 3 is a plan viewof the flat antenna member 66. In a case of corresponding to 8-inch sizewafer, the flat antenna member 66 is made of a metal disc having adiameter of 30-40 cm and a thickness of 1 to several millimeters. Morespecifically, the flat antenna member 66 is made of a metal plate suchas a silver plated copper plate or an aluminum plate.

The flat antenna member 66 is provided with a plurality of slots 84,which penetrate in the direction of thickness thereof and has a curvedplane configuration. As shown in FIG. 3, each of the slot 84 s has anelongated elliptic shape, and is arranged along three differentcircumferences P1, P2 and P3. It should be noted that although the slots84 are provided along the entire length of each of the circumferencesP1, P2 and P3, FIG. 3 shows only a part of the slots 84 for the sake ofsimplification. Here, the centers of the circumferences P1, P2 and P3are shifted from (eccentric to) the center of the outer shape of theflat antenna member 66 , and a direction of shift (direction ofeccentricity) of each circumference differs to each other.

That is, the direction of shift of the middle circumference P2 from thecenter of the outer configuration of the flat antenna member 66 isdifferent by 120 degrees from the direction of shift of the innercircumference P1 from the center of the outer configuration of the flatantenna member 66. Additionally, the direction of shift of the outercircumference P3 from the center of the outer configuration of the flatantenna member 66 is different by 120 degrees from the direction ofshift of the middle circumference P2 from the center of the outerconfiguration of the flat antenna member 66. Thus, the centers of thecircumferences P1, P2 and P3 are shifted in different directions to eachother.

Thus, when the slots are arranged along a plurality of non-concentriccircumferences, the surface waves, which propagate in the surface of thedielectric plate 62 and reflected by the outer periphery, return to thecentral part of the flat antenna member 66, but they are notconcentrated into a single point of the center of the flat antennamember 66. That is, the surface wave returns to a range having a certainarea in accordance with the amount of shift of the circumferences P1, P2and P3. Therefore, according to the arrangement of the slots in the flatantenna member 66 according to the present embodiment, unifromity ofelectron density is improved as compared to the conventional flatantenna member in which unevenness occurs in the electron density in aplasma space due to concentration of surface waves into a single pointwhen the circumference P1, P2 and P3 are concentric circles, and thedistribution of plasma density can be uniformized to a certain extent.

FIG. 4 is a graph showing a distribution ne of electron density in acase where the flat antenna member 66 according to the first embodimentof the present invention is used, and the distribution of electrondensity shown corresponds to a case where the slots are conventionallyarranged along concentric circumferences. As shown in FIG. 4, accordingto the flat antenna member 66 according to the first embodiment of thepresent invention which has the slots located in a non-concentricarrangement, the electron density in an area corresponding to thecentral part of the flat antenna member 66 is reduced and an areacorresponding to a peripheral part is increased as compared to thedistribution of electron density in the conventional case where theslots are located in the concentric arrangement. Therefore, according tothe flat antenna member 66 of the first embodiment of the presentinvention, the plasma density in a radial direction of the flat antennamember 66 (that is, a radial direction of the wafer W) is uniformized ascompared to the conventional case, and, thus, a uniform plasma processcan be applied to the wafer W.

Although the plane configuration of each slot 84 is made as an elongatedellipse in the case shown in FIG. 3, the present invention is notlimited to such a configuration, and, for example, a circular shape asshown in FIG. 5A may be used or an elliptic shape having differenteccentricity as shown in FIG. 5B may be used. Additionally, a pair ofshort sides of a rectangle may be formed as arcs as shown in FIG. 5C, oreach corner 84B of a triangle, a square or a rectangle may be formed ina curved shape as shown in FIG. 5D, FIG. 5E and FIG. 5F. Moreover,although not illustrated, each corner of a polygon having more than fivesides may be formed in a curved shape.

Since the plane configuration of each slot 84 does not contain an anglepart which tends to generate an electric-field concentration in theabove-mentioned cases, there is an effect in that an abnormal dischargeis prevented which permits supply of a large electric power.

Moreover, although the slot 84 shown in FIG. 3 is arranged so as toextend in a tangential direction,of a circumference, it may be arrangedwith a predetermined angle such as, for example, 45 degrees with respectto the tangential direction. Moreover, pairs of slots arranged inT-shape may be arranged along non-concentric circumferences. In a flatantenna member 66A shown in FIG. 6, slot pairs each of which consists ofslots 92A and 92B located in a T-shape are arranged along four pairs ofcircumferences (indicated by single-dashed chain lines in the figure).It should be noted that, in FIG. 6, the adjacent two circumferencesindicated by single-dashed chain lines make a pair, and thecircumferences making a pair are concentric to each other. Each slotpair 92 is formed by the slots 92A and slot 92B, which are arrangedalong the pair of circumferences.

Here, as for the four pairs of circumferences, the direction of shift(direction of eccentricity) differs by 90 degrees to each other. Thatis, the center of the innermost pair of circumferences is shifteddownward from the center O of the outer configuration of the flatantenna member 66A, and the center of the outer pair of thecircumferences is shifted leftward in the figure from the center O ofthe outer configuration of the flat antenna member 66A. Moreover, thecenter of the outer pair of circumferences is shifted upward from thecenter O of the outer configuration of the flat antenna member 66A.Furthermore, the center of the outermost pair of circumferences isshifted rightward from the center O of the outer configuration of theflat antenna member 66A. Therefore, similar to the flat antenna member66 shown in FIG. 3, surface waves reflected by the side surface of theflat antenna member are not concentrated into a single point, and theplasma density is prevented from being increased at the central part.

Here, the longitudinal direction of the slot 92A and the longitudinaldirection of the slot 92B are perpendicular to each other, and an end ofthe slot 92B is close to the center of the slot 92 a in the longitudinaldirection. Moreover, the longitudinal direction of the slot 92A inclinesby about 45 degrees to a line which connects the center section of theslot 92A and the center of the circumference along which the slot 92A isarranged, and, similarly, inclines by about 45 degrees to a line whichconnects the central section of the slot 92B and the center of thecircumference along which the slot 92B is arranged. According to such aT-shaped slot pair, a microwave propagating in a radial direction can beefficiently converted into a circular-deflected electric field, anduniform plasma can be generated efficiently.

Next, a description will be given, with reference to FIG. 7, of a secondembodiment of the present invention. FIG. 7 is a plan view of a flatantenna member 66B according to the second embodiment of the presentinvention.

Here, as shown in FIG. 2, when a gas for plasma is supplied from theside to the wafer W in the plasma processing apparatus, a deflection asshown in FIG. 8 is generated in the electron density of the plasmaspace. That is, the electron density on the upstream side in thedirection of supply of the gas for plasma is decreased, and the electrondensity on the downstream side is increased. Therefore, the plasmadensity tends to be nonuniform.

The flat antenna member 66B according to the second embodiment of thepresent invention solves the above-mentioned problem by taking thearrangement of the slots into consideration. That is, a deflection isintentionally given to the distribution of microwave radiation by givinga deflection to the arrangement of the slots so as to correct thedeflection in the distribution of plasma density due to a method ofsupplying a gas for plasma by the deflection of radiation of a microwaveby the flat antenna member.

The flat antenna member 66B shown in FIG. 7 has T-shaped slot pairs 92similar to the flat antenna member 66A shown in FIG. 6, and the centerof the pair of circumferences along which the pair of slots are arrangedare shifted from the center O of the flat antenna member 66B. However,in the flat antenna member 66B, the centers of all four pairs ofcircumferences are shifted in the same direction. In FIG. 7, althoughthe center of the innermost pair of circumferences aligns with thecenter of the flat antenna member 66B, the centers of all outer pairs ofcircumferences are shifted leftward, and the amount of shift isincreased toward outside.

Therefore, in the flat antenna member 66B shown in FIG. 7, the densityof the slot pairs 92 is high on the right side section, and is low onthe left side section. Thus, the microwave field intensity of theradiated microwave is set large on the right side section (where theslot density is high) of the flat antenna member 66B, and is set smallon the left side section (where the slot density is low) of the flatantenna member 66B.

Thus, in a case where the antenna member having slots of non-concentricarrangement as shown in FIG. 9, the deflection in the electron densitydue to the arrangement of the slots of the flat antenna member can becorrected by corresponding a section where the intensity of radiation ofa microwave is larger to a section where the electron density is smallerdue to a method of supplying a gas for plasma.

As mentioned above, also in the present embodiment, in the flat antennamember of a structure in which the slots are arranged along a pluralityof circumferences non-concentric to each other, a deflection in theelectron density generated by other causes can be corrected byintentionally generating a deflection of electron density by matchingthe direction of shift of each circumference, and, thus, uniform plasmacan be achieved.

It should be noted that, also in the second embodiment of the presentinvention, similar to the first embodiment, a single slot may be usedinstead of the slot pair, and the slot may have various planeconfigurations as shown in FIGS. 5A-5F.

The present invention is not limited to the above-mentioned specificallydisclosed embodiments, and variations and modifications may be madewithin the scope of the present invention.

What is claimed is:
 1. A microwave plasma processing apparatus whichapplies plasma processing to a substrate to be processed comprising: aprocess container provided therein with a placement stage on which thesubstrate to be processed is placed; a microwave generator whichgenerates a microwave and supplies said microwave to said processcontainer; and a microwave radiation member provided between themicrowave generator and said process container so as to radiate themicrowave to a space of said process container, wherein said microwaveradiation member has a plurality of slots arranged along a plurality ofcircumferences, and the plurality of circumferences are non-concentricto each other.
 2. A microwave plasma processing which applies plasmaprocessing to a substrate to be processed comprising: a processcontainer provided therein with a placement stage on which the substrateto be processed is placed; a microwave generator which generates amicrowave and supplies said microwave to said process container; and amicrowave radiation member provided between the microwave generator andsaid process container so as to radiate the microwave to a space of saidprocess container, wherein said microwave radiation member has aplurality of slots arranged alone a plurality of circumferences, and theplurality of circumferences are non-concentric to each other, andwherein the centers of said plurality of circumferences are eccentric indifferent directions to each other with respect to the center of saidmicrowave radiation member.
 3. The microwave plasma processing apparatusas claimed in claim 1, wherein the centers of said plurality ofcircumferences are eccentric in the same direction to each other withrespect to the center of said microwave radiation member, and an amountof eccentricity of the centers of said plurality of circumferencesincreases toward a periphery of said microwave radiation member.
 4. Themicrowave plasma processing apparatus as claimed in claim 1 or 3,wherein a slot pair is formed by one of said slots and an adjacent oneof said slots arranged in a T-shape, and a plurality of the slot pairsare arranged along said plurality of circumferences.
 5. A plasmaprocessing method using a microwave plasma processing apparatus whichapplies plasma processing to a substrate to be processed, comprising: aprocess container provided therein with a placement stage on which thesubstrate to be processed is placed; a microwave generator whichgenerates a microwave and supplies said microwave to said processcontainer; and a microwave radiation member provided between themicrowave generator and said process container so as to radiate themicrowave to a space of said process container, wherein said microwaveradiation member has a plurality of slots arranged along a plurality ofcircumferences, and the plurality of circumferences are non-concentricto each other, the method comprising: placing said substrate to beprocessed on said placement stage so that a processing surface of saidsubstrate faces said microwave radiation member; supplying the microwaveto said microwave radiation member so as to introduce the microwave intosaid process container through said non-concentrically arranged slots;and generating plasma in said process container by the introducedmicrowave so as to apply a plasma process to said substrate by thegenerated plasma.
 6. A microwave radiation member used for a microwaveplasma processing apparatus comprising a process container which appliesa plasma process and a microwave generator which generates a microwaveand supplies said microwave to said process container, wherein themicrowave radiation member is attached to said process container and isconnected to said microwave generator, and the microwave radiationmember has a plurality of slots arranged along a plurality ofcircumferences non-concentric to each other so as to introduce themicrowave into said process container through the plurality of slots. 7.A microwave radiation member used for a microwave plasma processingapparatus comprising a process container which applies a plasma processand a microwave generator which generates a microwave and supplies saidmicrowave to said process container, wherein the microwave radiationmember is attached to said process container and is connected to saidmicrowave generator, and the microwave radiation member has a pluralityof slots arranged alone a plurality of circumferences non-concentric toeach other so as to introduce the microwave into said process containerthrough the plurality of slots, wherein the centers of said plurality ofcircumferences are eccentric in different directions to each other withrespect to the center of said microwave radiation member.
 8. Themicrowave radiation member as claimed in claim 6, wherein the centers ofsaid plurality of circumferences are eccentric in the same direction toeach other with respect to the center of said microwave radiationmember, and an amount of eccentricity of the centers of said pluralityof circumferences increases toward a periphery of said microwaveradiation member.
 9. The microwave radiation member as claimed in claim6 or 8, wherein a slot pair is formed by one of said slots and anadjacent one of said slots arranged in a T-shape, and a plurality of theslot pairs are arranged along said plurality of circumferences.
 10. Themicrowave plasma processing apparatus as claimed in claim 2, wherein aslot pair is formed by one of said slots and an adjacent one of saidslots arranged in a T-shape, and a plurality of the slot pairs arearranged along said plurality of circumferences.
 11. The microwaveradiation member as claimed in claim 7, wherein a slot pair is formed byone of said slots and an adjacent one of said slots arranged in aT-shape, and a plurality of the slot pairs are arranged along saidplurality of circumferences.
 12. A microwave plasma processing apparatuswhich applies plasma processing to a substrate to be processedcomprising: a process container provided therein with a placement stageon which the substrate to be processed is placed; a microwave generatorwhich generates a microwave and supplies said microwave to said processcontainer; and a microwave radiation member provided between themicrowave generator and said process container so as to radiate themicrowave to a space of said process container, wherein said microwaveradiation member has a plurality of slots arranged along a plurality ofdiscrete circumferences, and the plurality of discrete circumferencesare non-concentric to each other.
 13. The microwave plasma processingapparatus as claimed in claim 12, wherein the centers of said pluralityof discrete circumferences are eccentric in different directions to eachother with respect to the center of said microwave radiation member. 14.The microwave plasma processing apparatus as claimed in claim 12,wherein the centers of said plurality of discrete circumferences areeccentric in the same direction to each other with respect to the centerof said microwave radiation member, and an amount of eccentricity of thecenters of said plurality of discrete circumferences increases toward aperiphery of said microwave radiation member.
 15. The microwave plasmaprocessing apparatus as claimed in any one of claims 12 to 14, wherein aslot pair is formed by one of said slots and an adjacent one of saidslots arranged in a T-shape, and a plurality of the slot pairs arearranged along said plurality of discrete circumferences.
 16. A plasmaprocessing method using a microwave plasma processing apparatus whichapplies plasma processing to a substrate to be processed, comprising: aprocess container provided therein with a placement stage on which thesubstrate to be processed is placed, a microwave generator whichgenerates a microwave and supplies said microwave to said processcontainer; and a microwave radiation member provided between themicrowave generator and said process container so as to radiate themicrowave to a space of said process container, wherein said microwaveradiation member has a plurality of slots arranged along a plurality ofdiscrete circumferences, and the plurality of discrete circumferencesare non-concentric to each other, the method comprising: placing saidsubstrate to be processed on said placement stage so that a processingsurface of said substrate faces said microwave radiation member;supplying the microwave to said microwave radiation member so as tointroduce the microwave into said process container through saidnon-concentrically arranged slots; and generating plasma in said processcontainer by the introduced microwave so as to apply a plasma process tosaid substrate by the generated plasma.
 17. A microwave radiation memberused for a microwave plasma processing apparatus comprising a processcontainer which applies a plasma process and a microwave generator whichgenerates a microwave and supplies said microwave to said processcontainer, wherein the microwave radiation member is attached to saidprocess container and is connected to said microwave generator, and themicrowave radiation member has a plurality of slots arranged along aplurality of discrete circumferences non-concentric to each other so asto introduce the microwave into said process container through theplurality of slots.
 18. The microwave radiation member as claimed inclaim 17, wherein the centers of said plurality of discretecircumferences are eccentric in different directions to each other withrespect to the center of said microwave radiation member.
 19. Themicrowave radiation member as claimed in claim 17, wherein the centersof said plurality of discrete circumferences are eccentric in the samedirection to each other with respect to the center of said microwaveradiation member, and an amount of eccentricity of the centers of saidplurality of discrete circumferences increases toward a periphery ofsaid microwave radiation member.
 20. The microwave radiation member asclaimed in one of claims 17 to 19, wherein a slot pair is formed by oneof said slots and an adjacent one of said slots arranged in a T-shape,and a plurality of the slot pairs are arranged along said plurality ofdiscrete circumferences.